1. Field of the Invention
The present invention relates to a method and an apparatus for feeding back channel information in a wireless communication system. More particularly, the present invention relates to a method and an apparatus for feeding back channel information having low complexity in a wireless communication system.
2. Description of the Related Art
A wireless communication system utilizes a structure for feeding back channel information in order to improve system performance, and research for improving the system performance through this structure is in constant progress. For example, the wireless communication system of the related art uses an Exponential Effective Signal to interference ratio Mapping (EESM)-based feedback method for allowing a terminal to report an effective Signal to Interference and Noise Ratio (SINR) to a base station, and at this point, an alternative for reducing feedback information is being studied and developed.
Accordingly, a technique for allowing a terminal to estimate a relation between a beta value β that changes depending on a Modulation and Coding Scheme (MCS) level and an effective SINR, and report the estimated relation information to a base station has been recently suggested. In this technique, when the terminal calculates an effective SINR for each beta value β, generates a function for estimating a relation between the beta value β and the effective SINR utilizing the calculated effective SINR, and reports the generated function to a base station, the base station calculates an effective SINR using a beta value β for each MCS level using the reported function, and selects an MCS level meeting a target error rate for the effective SINR.
However, as described above, although the method for reporting an effective SINR has an advantage of reducing feedback information, a current commercial system uses a structure for allowing a terminal to calculate an MCS level meeting an error rate and report CQI representing the MCS level, so that the above method cannot be applied.
Furthermore, the effective SINR calculating method using the EESM technique of the related art calculates an effective SINR using a beta value β for each MCS level, and determines an MCS level meeting a target error rate with respect to each effective SINR using an Additive White Gaussian Noise (AWGN) packet error performance curve. Accordingly, the effective SINR calculating method using the EESM technique of the related art has to perform a test for all MCS levels in order from a high MCS level to a low MCS level, thereby complicating the calculation process.
Therefore, a need exists for a method and an apparatus for feeding back channel information having low calculation complexity that is applicable to a current commercial system.